Recherche avancée

Sur d’autres sites (5877)

• FFmpeg, how to adjust color temperature ?

  23 mars 2018, par Dimka

  I am using ffmpeg with a camera and need to adjust colour temperature to the lighting, adjust to warm/cold/bright white.

  I know that there is colour balance filter, but it takes separate values for each colour, but it would be nice to take a Kelvin temperature (K) some way or other easy way.

  I’ve found an external algorithm that converts K into colours.

  Is there any embedded way to adjust colour temperature in ffmpeg ? It must be a popular feature ?

• ffmpeg : RGB to YUV conversion loses color and scale

  27 avril 2015, par learner

  I am trying to convert RGB frames to YUV420P format in ffmpeg/libav. Following is the code for conversion and also the images before and after conversion. The converted image loses all color information and also the scale changes significantly. Does anybody have idea how to handle this ? I am completely new to ffmpeg/libav !

  // Did we get a video frame?
  
     if(frameFinished)
  
     {
  
         i++;
  
         sws_scale(img_convert_ctx, (const uint8_t * const *)pFrame->data,
  
                   pFrame->linesize, 0, pCodecCtx->height,
  
                   pFrameRGB->data, pFrameRGB->linesize);                   
  
  
  
         //==============================================================
  
         AVFrame *pFrameYUV = avcodec_alloc_frame();
  
         // Determine required buffer size and allocate buffer
  
         int numBytes2 = avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,                                 
  
                                            pCodecCtx->height);
  
         uint8_t *buffer = (uint8_t *)av_malloc(numBytes2*sizeof(uint8_t));
  
  
  
         avpicture_fill((AVPicture *)pFrameYUV, buffer, PIX_FMT_RGB24,
  
                         pCodecCtx->width, pCodecCtx->height);
  
  
  
  
  
         rgb_to_yuv_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,  
  
                                         PIX_FMT_RGB24,
  
                                         pCodecCtx->width,pCodecCtx->height, 
  
                                         PIX_FMT_RGB24,
  
                                         SWS_BICUBIC, NULL,NULL,NULL);
  
  
  
         sws_scale(rgb_to_yuv_ctx, pFrameRGB->data, pFrameRGB->linesize, 0, 
  
                   pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
  
  
  
         sws_freeContext(rgb_to_yuv_ctx);
  
  
  
         SaveFrame(pFrameYUV, pCodecCtx->width, pCodecCtx->height, i);
  
  
  
         av_free(buffer);
  
         av_free(pFrameYUV);
  
     }

  

  

• ffmpeg : how add constant color margin to a video

  24 octobre 2017, par علیرضا

  i have a video and i want to add a black background padding to top and bottom of the video to getting a square output.
  
  is it possible to do this with ffmpeg ?